Not Applicable
Not Applicable
Portions of the material in this patent document are subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office file or records, but otherwise reserves all copyrights whatsoever.
1. Field of the Invention
The invention relates generally to acoustical sensing of glass-breakage, and specifically to providing electronic glass-break detection having improved discrimination of glass flexing to reduce false triggering.
2. Description of the Background Art
The detection of glass-breakage events by sensing and processing acoustical waves which are the result of a contact force being applied to a contact-sensitive-surface is well known in the art. In a few alarm systems, glass-breakage has additionally been detected as a flex pressure wave followed by high-frequency breakage acoustics. Although these methods provide a measure of breakage discrimination they are unable to discriminate numerous non-glass-breakage events, such as impact and laminated glass acoustic patterns, typically exemplified by type 1 and type 2 impact events which are similar to impacts defined by Underwriters Laboratory of Canada (ULC).
Therefore, a need exists for a glass-breakage detection circuitry that provides for proper discrimination of non-glass-breakage events as detected by an acoustical transducer. The present invention satisfies those needs, as well as others, and overcomes the deficiencies of previously developed discrimination circuits.
The present invention is capable of providing increased discrimination of impacts which do not cause panel breakage. The detection method and system of the invention provides improved discrimination of breakage events and thereby reduces triggering of false alarms. Acoustical signals generated by an event are processed in real-time according to a method of validation that is highly selective to actual breakage events while discriminating against glass-flexure and other common non-glass-breakage events.
An object of the invention is to improve false trigger immunity when detecting breakage events acoustically.
Another object of the invention is to provide a dual-trigger method that prevents the errant triggering of an acoustical event.
Another object of the invention is to provide false trigger immunity from glass-flexing events, such as type 1 and type 2 vibrations resulting from an impact in which the glass does not break.
Another object of the invention is to provide alarm detection of breakage events within laminated windows and similar laminated structures while differentiating similar characteristics of non-breakage events within non-laminated structures.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.